Tian Houkuan, Yang Yuhui, Ding Jia, Liu Wanglong, Zuo Biao, Yang Juping, Wang Xinping
Department of Chemistry, Key Laboratory of Advanced Textile Materials and Manufacturing Technology of the Education Ministry, Zhejiang Sci-Tech University, Hangzhou 310018, China.
Soft Matter. 2014 Sep 7;10(33):6347-56. doi: 10.1039/c4sm00918e.
The effect of the concentration of casting solutions on the surface dynamics of the corresponding spin-coated poly(methyl methacrylate) (PMMA) film was investigated by measuring the surface reorganization of fluorine tracer-labeled PMMA. The onset temperature of fluorinated PMMA chain end reorganization (T(onsetR)) was identified and is shown to depend on the PMMA concentration in the film-forming solution. It was found that the surface T(onsetR) and relaxation activation energy E(a) of the PMMA films prepared from 4.2 wt% PMMA cyclohexanone solution are 70 °C and 260 kJ mol(-1), respectively, which are higher than those of the PMMA films prepared from 0.8 wt% PMMA cyclohexanone solution (55 °C and 144 kJ mol(-1), respectively). The T(onsetR) and E(a) of PMMA films increased with increasing concentration of casting solutions within the range of 1.8 wt% to 4 wt%. The chain entanglement of PMMA chains is proposed to be the speculative origin for these observed depressed dynamics of poly(methyl methacrylate) chains on the films' surface prepared using casting solutions of various concentrations.
通过测量氟示踪剂标记的聚甲基丙烯酸甲酯（PMMA）的表面重组，研究了浇铸溶液浓度对相应旋涂聚甲基丙烯酸甲酯（PMMA）薄膜表面动力学的影响。确定了氟化PMMA链端重组的起始温度（T(onsetR)），结果表明它取决于成膜溶液中PMMA的浓度。发现由4.2 wt% PMMA环己酮溶液制备的PMMA薄膜的表面T(onsetR)和弛豫活化能E(a)分别为70°C和260 kJ mol(-1)，高于由0.8 wt% PMMA环己酮溶液制备的PMMA薄膜（分别为55°C和144 kJ mol(-1)）。在1.8 wt%至4 wt%的范围内，PMMA薄膜的T(onsetR)和E(a)随浇铸溶液浓度的增加而增加。PMMA链的链缠结被认为是在使用不同浓度浇铸溶液制备的薄膜表面上观察到的聚甲基丙烯酸甲酯链动力学降低的推测原因。
